1. Field of the Invention
This invention relates to systems for charging breathing apparatus cylinders and, more particularly, to such a system for automatically transporting a cylinder into a containment chamber, charging the cylinder, and transporting it out of the chamber for use.
2. Description of the Related Art
Compressed air for breathing is stored in portable cylinders ("air bottles") and used by Scuba divers and fire fighters, the principal users of such air bottles. For Scuba divers the cylinders are usually charged to either 2250 or 3000 pounds per square inch (psi), depending on the cylinder structure, in a water tank to provide cooling. Bottles for fire fighter use are typically charged to 2350, 3000 or 4500 psi in a dry environment. The cylinders for storing breathing air must be inspected at regular intervals and are also subjected to periodic hydrostatic testing. Despite these precautions, cylinders do occasionally rupture and it is therefore important to provide for the containment of explosive discharge of fragments and compressed air on such an occasion and to protect personnel and equipment in the near vicinity.
The charging systems which are delivered for use by fire departments are generally more sophisticated and more foolproof, principally because of the higher pressures and more frequent cycling of the cylinders, than those in dive shops. A number of companies manufacture cylinder refill systems of the type described. For example, Mako Compressors, Inc. of Ocala, Fla. markets a line of fill stations of varying degrees of complexity and sophistication under the MAKO trademark. Ingersoll-Rand Company, Breathing Air Division, of Pleasant Garden, N.C. markets cylinder refill systems under its TALON and BARON II trademarks. American Bristol Industries, Inc. of Harbor City, Calif. produces air charging systems in both stationary and mobile units, the latter being available in trailer- and truck-mounted versions, for use by fire departments.
Each of these units presently on the market presents one particular drawback: the cylinders must be lifted over a lip or threshold which is located at about hip height on the average person. The need to lift a relatively heavy cylinder over the hip-high threshold to place the cylinder in position for filling places undue demand on the physical capabilities of the individuals involved, particularly when it may be necessary for a particular individual to handle a significant number of cylinders during the charging process. It would be a definite improvement in systems of the type described if a way were found to accommodate the introduction of the cylinders into the fill chamber without the need to lift them to hip height or higher during their handling. It would also be an improvement over present systems if the charging process could be made safer and more automated, as well as accelerated in operation.